CUTTING OUT THE DETECTOR TAP

Radio Record, Volume II, Issue 1, 20 July 1928, Page 13

CUTTING OUT THE DETECTOR TAP

N order to do away with the unequal drain caused on B batteries by the detector tap, or the extra high resistances required in B eliminators. to sufficiently reduce detector voltage, a good plan is to employ a first audio stage of resistance coupling. By this means the B voltage need not be cut down by external resistances, as the coupling resistance will do all that is required. In such a case a higher resistance than the 100,000 ohms. usually employed may he used, and 2 or 3 megohms will be found to work well and give high amplification with a saving of B eurrent. The couplng condenser — be‘tween plate and grid may be a halfmicrofarad, which will efficiently pass the lower audio frequencies. It is ‘also necessary that the grid leak on the first audio tube should be as high as will work without "blocking," which would soon be indicated by distortion or motor-boating, If this change is made according to the lines indicated, and a high-mu yalve used as detector, amplification "will be fully as great as that obtained from a transformer, and the gain in ‘quality will depend somewhat upon the type of transformer replaced.

(THE International Bible . Students’ Association arranged for May 80 what is believed will be the greatest radio hook-up to that time in. America. More than 100 stations were linked together to hear an address at Albany by Joseph F. Rutherford, president of the organisation. The key station was WBZ, Boston. ADIO, infant of the arts, is steadily gaining favour in Greece, ancient mother of the arts. Receiving sets imported in the last year were yalued at £10,000. Sets manufactured in France lead the list of Greek imports with 105, the United States is second with 47, Germany third with 29, and Great Britain fourth with 19. ‘THE bullfight as broadcast by Spanish stations is the favourite radio diversion of the large Spanish colony in Paris. Before the fight is heard 3 talk by the toreador, then a description of the weather and of the crowd, and finally the shouting as the fight proceeds and acclamation of the hero of the day. Woy one soldered joint has to be made close to another one, & damp rag wrapped round the latter will tend to prevent it becoming heated and unsoldered. FARTHENWARE jars should not. be used as wet-battery containers, ag there is much more leakage with these than with glass.